1. Field of the Invention
The present invention relates to a nylon polarized lens and a moulding mold thereof.
2. Description of the Prior Art
Most conventional polarized lenses are made of PC material (polycarbonate) because the PC lenses are light, durable and environmental-friendly. The weight of the PC lens is about one tenth of the weight of a glass lens and half of the weight of a resin lens. The PC lens has the physical properties of anti-strike and anti-deformation, which won't break and is a safe lens. The thermosetting plastic can be recycled for other products. But, the PC lens doesn't have the property of anti-acidity, so it can't be used for popular frames. During injection, the PC polarized lens will is generate inner stress. When assembled to an eyeglasses frame, the PC lens has the phenomenon of stress concentration, particularly, to a metal frame. Even if it is not obvious when assembled, the phenomenon of stress concentration still exists after the plastic frame is used for a period of time. The color of the edge of the lens may change, or the lens may break. The PC material is not adapted for drilling. Therefore, the polarized lens must be improved.
Nylon lens is also light, endurable and environmental-friendly and has low stress. Compared to the PC lens, the nylon lens can be processed better for expensive lenses. The current trend is to use nylon material for manufacturing high-class polarized lenses.
Chinese Utility Model Patent No. 200620118294.9 is the applicant's invention for connection of polarized film and lens, titled “mold device to form eyeglasses lens and eyeglasses lens. As shown in FIG. 1, a polarized lens 10 is formed with four recesses 20 (positioning portions) at four corners thereof. An outer surface of an area surrounded by the four recesses 20 is adapted to bond a polarized film 30. This patent also discloses a mold device to form the eyeglasses lens. As shown in FIG. 2, the mold device comprises a lower ide 40 and an upper die 60. The top surface of the lower die 40 is formed with four protruding portions 50 (corresponding to the positioning portions) at four corners thereof. The area surrounded by the four protruding portions 50 is adapted to bond the polarized film 30. The upper die 60 cooperates with the lower die 40 to form a space for injecting melting plastic to be hardened as the eyeglasses lens 10. During processing, the polarized film 30 is secured on the lower die 40 by the protruding portions 50, and then the upper die 60 and the lower die 40 are closed to form the injection space S for injection. As shown in FIG. 3, the melting plastic and the polarized film 30 are bonded together to be the polarized lens 10. As shown in FIG. 4, a layer of adhesive glue 70 is attached to the surface of the polarized film 30. When the polarized film 30 is cut, the adhesive force of the adhesive glue 70 is lowered. During injection, as shown in FIG. 5, the melting plastic 70 is poured into the injection space S, which is directly is flushed to the edge of the polarized film 30 and may flush the adhesive glue 70 away. The surface of the lens may have ripples as shown in FIG. 6 to influence the quality of products. In order to avoid the glue to be flushed away, a plastic layer 90 is attached to the adhesive glue 70 of the polarized film 30. As shown in FIG. 7, through the protection of the plastic layer 90, the adhesive glue 70 won't be flushed away by the melting plastic 80 during injection. In this way, the quality of products can be ensured to increase the yield rate. However, the thickness of the lens is about 3 mm. This patent is not adapted to manufacture thin polarized lenses. The lens uses more material, so it is not applied to expensive polarized lenses, such as nylon polarized lenses. It is necessary to improve the nylon polarized lens structure and the moulding mold thereof. Accordingly, the inventor of the present invention has devoted himself based on his many years of practical experiences to solve these problems.